The solution structure of several pure E. coli tRNAs will be studied by high-resolution (360 MHz) NMR spectroscopy. Four pure aminoacyl-tRNA synthetases from B. stearothermophilus have been isolated and are being characterized in terms of biochemical and ligand binding properties. Four synthetase-tRNA complexes will be studied by NMR sppctroscopy. The conformational dynamics of individual base pairs in various tRNA speciesare being studied by saturation recovery experiments using the Redfield 214 pulsed FTNMR techniques.